1. Field of the Invention
The present invention relates to a floating cover roof, and more particularly to a floating cover roof for a storage tank to reduce the VOC (volatile organic component) loss and enhance the structural strength of the floating cover roof.
2. Description of Related Art
A conventional storage tank has a tank shell and a floating cover roof. The tank shell is hollow and is used to storage fluid and has an internal surface. The floating cover roof floats on the surface of the storage fluid that is stored inside of the tank and can be moved upward or downward relative to the tank shell based on the height of the storage fluid and has an outer periphery and a sealing ring. The sealing ring is mounted around the outer periphery of the floating cover roof and abuts the internal surface of the tank to prevent the VOC escaping from the storage tank.
Two kinds of the conventional floating cover roofs are provided in the market. One kind of conventional floating cover roof has multiple pontoons to make the floating cover roof float over the surface of the storage fluid. However, the pontoons will form a gap between the floating cover roof and the surface of the storage fluid and this will cause the VOC loss easily.
With reference to FIG. 7, the other kind of conventional floating cover roof has multiple floating units 30 to make the floating cover roof float over the surface of the storage fluid. Each floating unit 30 has a honeycomb core 31 and two flat plates 32. The honeycomb core 31 has a top and a bottom. The flat plates 32 are respectively mounted on the top and the bottom of the honeycomb core 31. Thus, the conventional floating cover roof can float on and abut the surface of the storage fluid to prevent the VOC loss from the conventional floating cover roof. However, the flat plates 32 of each floating unit 30 are securely mounted on the corresponding honeycomb core 31 by glue, and the storage fluid may decompose the glue and cause the flat plates 32 to separate from the honeycomb core 31. In addition, the plates 31, 32 of each floating unit 30 can be securely connected to each other by high temperature melting operation. However, the high temperature melting operation needs an expensive high temperature melting apparatus to connect the plates 31, 32 with each other and this will increase the cost of production.
The floating cover roof for storage tank in accordance with the present invention mitigates or obviates the aforementioned problems.